Exploiting Deep Features for Remote Sensing Image Retrieval: A Systematic Investigation

Remote sensing (RS) image retrieval is of great significant for geological information mining. Over the past two decades, a large amount of research on this task has been carried out, which mainly focuses on the following three core issues: feature extraction, similarity metric and relevance feedback. Due to the complexity and multiformity of ground objects in high-resolution remote sensing (HRRS) images, there is still room for improvement in the current retrieval approaches. In this paper, we analyze the three core issues of RS image retrieval and provide a comprehensive review on existing methods. Furthermore, for the goal to advance the state-of-the-art in HRRS image retrieval, we focus on the feature extraction issue and delve how to use powerful deep representations to address this task. We conduct systematic investigation on evaluating correlative factors that may affect the performance of deep features. By optimizing each factor, we acquire remarkable retrieval results on publicly available HRRS datasets. Finally, we explain the experimental phenomenon in detail and draw conclusions according to our analysis. Our work can serve as a guiding role for the research of content-based RS image retrieval

Colossal Trajectory Mining: A unifying approach to mine behavioral mobility patterns

Spatio-temporal mobility patterns are at the core of strategic applications such as urban planning and monitoring. Depending on the strength of spatio-temporal constraints, different mobility patterns can be defined. While existing approaches work well in the extraction of groups of objects sharing fine-grained paths, the huge volume of large-scale data asks for coarse-grained solutions. In this paper, we introduce Colossal Trajectory Mining (CTM) to efficiently extract heterogeneous mobility patterns out of a multidimensional space that, along with space and time dimensions, can consider additional trajectory features (e.g., means of transport or activity) to characterize behavioral mobility patterns. The algorithm is natively designed in a distributed fashion, and the experimental evaluation shows its scalability with respect to the involved features and the cardinality of the trajectory dataset

Research and Education in Computational Science and Engineering

Over the past two decades the field of computational science and engineering (CSE) has penetrated both basic and applied research in academia, industry, and laboratories to advance discovery, optimize systems, support decision-makers, and educate the scientific and engineering workforce. Informed by centuries of theory and experiment, CSE performs computational experiments to answer questions that neither theory nor experiment alone is equipped to answer. CSE provides scientists and engineers of all persuasions with algorithmic inventions and software systems that transcend disciplines and scales. Carried on a wave of digital technology, CSE brings the power of parallelism to bear on troves of data. Mathematics-based advanced computing has become a prevalent means of discovery and innovation in essentially all areas of science, engineering, technology, and society; and the CSE community is at the core of this transformation. However, a combination of disruptive developments---including the architectural complexity of extreme-scale computing, the data revolution that engulfs the planet, and the specialization required to follow the applications to new frontiers---is redefining the scope and reach of the CSE endeavor. This report describes the rapid expansion of CSE and the challenges to sustaining its bold advances. The report also presents strategies and directions for CSE research and education for the next decade.Comment: Major revision, to appear in SIAM Revie

Dynamical Patterns of Cattle Trade Movements

Despite their importance for the spread of zoonotic diseases, our understanding of the dynamical aspects characterizing the movements of farmed animal populations remains limited as these systems are traditionally studied as static objects and through simplified approximations. By leveraging on the network science approach, here we are able for the first time to fully analyze the longitudinal dataset of Italian cattle movements that reports the mobility of individual animals among farms on a daily basis. The complexity and inter-relations between topology, function and dynamical nature of the system are characterized at different spatial and time resolutions, in order to uncover patterns and vulnerabilities fundamental for the definition of targeted prevention and control measures for zoonotic diseases. Results show how the stationarity of statistical distributions coexists with a strong and non-trivial evolutionary dynamics at the node and link levels, on all timescales. Traditional static views of the displacement network hide important patterns of structural changes affecting nodes' centrality and farms' spreading potential, thus limiting the efficiency of interventions based on partial longitudinal information. By fully taking into account the longitudinal dimension, we propose a novel definition of dynamical motifs that is able to uncover the presence of a temporal arrow describing the evolution of the system and the causality patterns of its displacements, shedding light on mechanisms that may play a crucial role in the definition of preventive actions

Dynamical Patterns of Cattle Trade Movements

Despite their importance for the spread of zoonotic diseases, our understanding of the dynamical aspects characterizing the movements of farmed animal populations remains limited as these systems are traditionally studied as static objects and through simplified approximations. By leveraging on the network science approach, here we are able for the first time to fully analyze the longitudinal dataset of Italian cattle movements that reports the mobility of individual animals among farms on a daily basis. The complexity and inter-relations between topology, function and dynamical nature of the system are characterized at different spatial and time resolutions, in order to uncover patterns and vulnerabilities fundamental for the definition of targeted prevention and control measures for zoonotic diseases. Results show how the stationarity of statistical distributions coexists with a strong and non-trivial evolutionary dynamics at the node and link levels, on all timescales. Traditional static views of the displacement network hide important patterns of structural changes affecting nodes' centrality and farms' spreading potential, thus limiting the efficiency of interventions based on partial longitudinal information. By fully taking into account the longitudinal dimension, we propose a novel definition of dynamical motifs that is able to uncover the presence of a temporal arrow describing the evolution of the system and the causality patterns of its displacements, shedding light on mechanisms that may play a crucial role in the definition of preventive actions

Systematic conservation planning in marine environments: sensitivities of the planning framework to aspects of scale

Problems of scale abound in the science, governance, and conservation planning of complex social-ecological systems. In systematic conservation planning processes, which aim to effectively and efficiently allocate conservation interventions in space and time, nearly half of the stages in the planning framework involve decisions directly related to scale. The implications of scale-related problems are still poorly understood by conservation planners and researchers, as well as approaches to deal with these problems and integrate explicit multiscale thinking into the planning process. Thus, the overall goal of this thesis is to improve understanding of the different influences of scale on conservation planning outcomes, with the ultimate goal of making specific recommendations to improve the conservation planning framework to deal with scale more explicitly. As such, the structure of this thesis mirrors the relevant stages in the planning framework that involve scale-explicit decisions, organized by the two groups of scale considerations: technical versus practical. The first research objective of my thesis seeks to understand the extent to which technical aspects of setting spatial priorities for marine conservation ('spatial prioritisations') influence where priorities are determined, and how this relates to conservation strategies that rely on broad, coarse-resolution prioritisations to guide the locations of finer-resolution priorities are actions. I address this objective in Chapter 2 by quantifying the individual and interacting effects of three prioritisation factors on spatial priorities for marine conservation: (1) planning-unit size, (2) thematic resolution of coral reef classes, and (3) spatial variability of socioeconomic costs. I used Fiji and Micronesia as case studies and found that all three factors influenced spatial priorities to different extents, with the spatial variability of socioeconomic costs having the largest influence, followed by planning-unit size and thematic resolution of reef classes. Furthermore, I identified an interaction effect between the thematic resolution of reef classes and the socioeconomic cost data used. These findings have important implications for the strategy of relying on coarse-resolution prioritisations to guide finer-resolution assessments and invalidate a number of implicit assumptions that are made when adopting such strategy. Progressing to practical considerations of scale, my second research objective seeks to investigate the implications of another strategy commonly assumed or proposed to overcome scale mismatches between regional and local perspectives: dynamically iterating between regionalextent planning and locally applied actions ('iterative planning'), as conservation plans are incrementally implemented across a region. To address this objective in Chapter 3, I specifically explore how frequently regional priorities should be updated as local actions are gradually implemented. Using Fiji as a case study region, I found that changes in the frequency of updating regional priorities did not influence the total time taken to achieve conservation objectives, or the total extent of final reserve systems. However, I did identify two potential benefits to updating priorities more frequently: faster achievement of objectives for high-priority features, and greater potential to capitalise on areas that have previously had conservation efforts applied. This work provides insights into trade-offs to consider regarding the frequency of updating regional conservation assessments, which vary depending on specific planning contexts. My third research objective seeks to determine if there is an optimal scale at which to conduct conservation planning, as a precursor to understanding how best to integrate planning across multiple scales ('multiscale conservation planning'). I address this in Chapter 4 by elucidating the respective strengths and weaknesses of conservation plans developed at different jurisdictional levels in the Coral Triangle region (e.g., local, national) to adequately consider multiple social and ecological scales. I found that no plans I assessed were able to adequately address all social and ecological scales, and that plans generally best addressed social and ecological components representative of the same level at which the plan was developed. This research adds nuanced appreciation of the limitations of lower- versus higher-level conservation planning. While these respective limitations are understood as the general inability to consider components at other scales, I demonstrate that these limitations can be attributed to differences in technical versus conceptual abilities. My findings demonstrate the necessity for vertical integration between planning levels as a means to overcome their respective limitations. The fourth and final research objective of my thesis seeks to investigate the concept of multiscale conservation planning. It is overwhelmingly evident that the consideration and understanding of any social and ecological system must consider multiple scales explicitly. Thus, my thesis culminates in Chapter 5 with a theoretical and empirical examination of what it might mean to conduct multiscale conservation planning, a critical frontier in this field. Using Papua New Guinea and the Solomon Islands as case studies, I provide empirical evidence that refutes the conventional notion that conservation planning across multiple scales occurs unidirectionally ('scaling up' versus 'scaling down') and present a novel archetype that more realistically reflects multiscale planning in practice: 'multidirectional scaling'. I also evaluate factors that impeded or facilitated successful outcomes across multiple scales and reveal six scale-explicit characteristics for effective multiscale planning, the first two of which are novel concepts to the literature: (1) multiscale understanding, (2) scale jumping, (3) leadership characteristics, (4) stakeholder engagement, (5) policy frameworks, and (6) institutional settings. I propose these six characteristics constitute a new form of conservation capital, 'scalar capital', as a necessary resource or investment for successful outcomes across multiple scales. My thesis contributes nuanced understanding of the sensitivities of the conservation planning framework to aspects of scale, in both theory and practice. I offer specific recommendations for each of the relevant stages in the conservation planning framework that involve scale-explicit concerns and illuminate some implications of existing problems and influences of scale. Essentially, it is the aim of my thesis to conduct research that can enable conservation practitioners to consider aspects of scale more explicitly and improve the efficacy of conservation planning outcomes. Conservation planning in practice must progress to view any system to manage and govern as inherently complex and multiscale; similarly, planning processes across multiple scales should adopt a 'planning system identity' (such as in complex systems) to correspond in design with the systems that they seek to manage